[meteorite-list] Saturn's Spokes: Spawned by Storms?

From: Gerald Flaherty <grf2_at_meteoritecentral.com>
Date: Thu, 19 Apr 2007 20:42:45 -0400
Message-ID: <00b201c782e4$d195ac70$6402a8c0_at_Dell>

Laboratory in Dorking, Dorking?????????????
Jerry Flaherty
----- Original Message -----
From: "Ron Baalke" <baalke at zagami.jpl.nasa.gov>
To: "Meteorite Mailing List" <meteorite-list at meteoritecentral.com>
Sent: Thursday, April 19, 2007 7:02 PM
Subject: [meteorite-list] Saturn's Spokes: Spawned by Storms?

> http://sciencenow.sciencemag.org/cgi/content/full/2007/419/1
> Saturn's Spokes: Spawned by Storms?
> By Govert Schilling
> ScienceNOW Daily News
> 19 April 2007
> PRESTON, U.K.--Dark, radial spokes in the rings of Saturn have puzzled
> planetary astronomers ever since they were discovered by the Voyager
> spacecraft in the early 1980's. Today, at the Royal Astronomical Society
> National Astronomy Meeting here, scientists described how the enigmatic
> features could be caused by thunderstorms and lightning. "It's one of
> the best theories I've heard so far," says Carl Murray of Queen Mary
> University of London.
> The spokes are clouds of electrostatically charged dust particles that
> float above and below the ring plane. But there's no consensus on how
> they form. Astronomers have suggested that meteorite impacts or solar
> wind particles may do the charging, but no single theory has been able
> to explain all the observed characteristics of the spokes, such as their
> locations, shapes, clustering behavior, and--most notably--their
> puzzling absence between October 1998 and September 2005.
> Enter the thunderstorm model, proposed by Geraint Jones of the Mullard
> Space Science Laboratory in Dorking, U.K., and colleagues, and presented
> at the meeting by team member Christopher Arridge. According to this
> idea, energetic beams of electrons produced above these storms are
> transported to the rings by Saturn's magnetic field, where they charge
> the dust and lift it out of the ring plane. If the storms occur at
> approximately 43 degrees latitude north or south, the electrons end up
> in a part of the ring that rotates at the same speed as the planet, so
> spokes can build up. Their absence between 1998 and 2005--about one
> quarter of a Saturnian year--may be just a seasonal effect in the
> occurrence of thunderstorms at this particular latitude, the astronomers
> speculate.
> The thunderstorm model nicely explains why spokes occur in groups, says
> spoke expert Colin Mitchell of the Space Science Institute in Boulder,
> Colorado. But, he says, it doesn't account for the very narrow spokes
> that are also observed. "Spokes seem to be a pretty complicated
> problem," says Mitchell. "We definitely don't have the final word yet."
> Confirmation could come from NASA's Cassini probe, which is orbiting
> Saturn. If a thunderstorm is seen at the same time and the right
> location, Mitchell says, "that would be an indicator that the model is a
> good starting point."
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Received on Thu 19 Apr 2007 08:42:45 PM PDT

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